It’s not uncommon for brand new valves to need an adjustment after breaking them in if the valve seats weren’t redone. Sort of like cutting their own grooves in the old seats. Adjust them again and they should last.
If they still go out of adjustment, then either the seats are wasted or they may have lapped them, which shouldn’t be done with coated valves. Even with lapping them, they should still last much longer than that.
94mm bbk, +4 stroker, Hot Cams, Vertex piston, FMF Power Bomb header and Power Core can, KW black diamond valves/dual springs, FCR39, K&N, Elka long-travel LT fronts and rear, Houser +3, +3/4 LT A-arms, American Star pro xs chromoly tie rods, Dyna non-programable, Tusk +3 axle.